The mass culture of cells has recently been required with progression of stem cell research and regenerative medicine and development of biopharmaceuticals such as antibody drugs. Recent mass culture of cells uses culture tanks, such as bioreactors (see Patent Literature 1, for example), or cell culture bags (see Patent Literature 2, for example) made of gas-permeable materials, instead of flasks or petri dishes for cell culture.
Cells intake oxygen, nutrition, and other components needed for their growth and excrete carbon dioxide and waste products during cell culture. For this reason, culturing cells for a long period of time degrades culture media and requires culture media to be regularly changed.
To prepare clinically-used cells, for example, culture conforming to severe requirements is needed and thus culture in closed systems, which decreases contamination, is effective although the change of culture media in closed systems during cell culture is very difficult.
For the culture of floating cells, changing culture media requires separation of culture media and cells by centrifugation or other techniques.